There's a phenomenon in scientific research that sometimes the act of performing or observing the experiment affects the outcome. To take a simple example, suppose a researcher wants to know the temperature of some liquid. So he inserts a thermometer. But the thermometer itself has some temperature, and so the act of inserting the thermometer may alter the temperature of the liquid. Or if you were trying to study whether people behave irrationally in some situation, if the subjects know you are observing them, they may be more careful in their behavior because they don't want to embarrass themselves in front of strangers. Etc.

Is there a word or term for this phenomenon?

1 Answer 1



Hawthorne effect, (a sub-class of observer effects) is a form of reactivity in which subjects modify an aspect of their behavior, in response to their knowing that they are being studied.

AS in:

Due to the Hawthorne effect, the subjects were more careful in their behavior because they knew they were being observed.

  • "Observer effect" (which you link to) is the more general answer, while the "Hawthorne effect" is specific to human psychology. I suggest editing the answer to reflect this distinction since the question is not specific to human psychology.
    – Ratler
    Aug 14, 2018 at 18:55
  • so noted and edited
    – lbf
    Aug 14, 2018 at 19:05
  • 1
    And the thermometer example in the question is a probe effect. Aug 15, 2018 at 0:58

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